Field of the Invention
The present invention relates to a shift drum angle detecting device for a transmission.
Discussion of the Background
In a transmission of a dual clutch (hereinafter referred to as DCT) type conventionally used in a vehicle, shift forks moved by rotation of a shift drum provided to a change mechanism of the transmission move shifter gears of the transmission, whereby speed change operation is performed (see Japanese Patent Laid-Open No. 2009-156375). The shift drum is provided with a star-shaped cam that is rotated integrally with the shift drum. A cam profile in which a plurality of projections and depressions are alternately arranged at fixed intervals is formed on the outer circumferential surface of the star-shaped cam. A roller of a stopper is pressed against the cam profile. When the shift drum is rotated by a predetermined amount, the roller is pressed against a recessed surface of the cam profile which recessed surface is set at a gear position, so that the shift drum is securely stopped at the set gear position.
In the transmission of the conventional DCT type, when a speed change is made from a first speed to a second speed, the gear position of the shift drum changes from a first speed position (1-N) through a first speed-second speed preparatory speed change position (1-2) to a second speed position (N-2). The transmission has shift stages of six speeds. The shift drum is provided with 12 gear positions (N-N, 1-N, 1-2, N-2, 3-2, 3-N, 3-4, N-4, 5-4, 5-N, 5-6, and N-6) including a neutral position, six speed positions, and preparatory speed change positions. The 12 gear positions are provided at fixed intervals for one rotation of the shift drum. The intervals of the gear positions are therefore intervals of 30 degrees. A gear position sensor as an angle sensor formed by a potentiometer provided to the shift drum needs to detect the intervals of 30 degrees.